Yes, Australia did. Go to any forum that discusses this and you'll read that if given the choice once more, most would object. Speaking of AK47s. there are twice the number of deaths each year with hammers vs AK47s.
I'm sure there will be a day that some far leftist will gather enough strength to push for 'regulations' but DCs and Chcago's gun law was recently challenged and both failed miserably. These are two huge BLUE counties in this country.
Specifically, what regulations would you submit and push for?
I think I've already suggested some regulations. I suspect that we will eventually impose more extensive background checks, and I would anticipate that a lot of the open carry of handguns will be regulated. Although not a lot of AK47s are used in murders, the damage when they are used would be limited if the AK47 had not been the weapon. The mass murder situations like schools and theaters are more difficult if the available weapon is a shotgun or rifle.
You fell a little into the "plaino"-type language when you spoke of leftists wanting gun regulation. A lot of the push is being made by law enforcement agencies who don't want to be facing automatic weapons. These are hardly leftist.
Although this is not likely to come up in the near future, constitutional scholars are definitely not in agreement about the meaning of the second amendment wording, "A well-regulated militia being necessary to the security of a free state, the right of the people to keep and bear arms shall not be infringed."
Does this mean that individuals are granted the right to bear arms? Does it mean that the right to bear arms has something to do with a militia? Does it assume that the reason for bearing arms is the necessity of a militia for the security of free state? There are a lot of questions that are not resolved, and it is not exactly clear what the intent was when the amendment was written. This is not settled law and will likely undergo a good number of court decisions in the future. Don't forget that "conservative" presidents have proposed gun control. It isn't necessarily a leftist issue.